The Stanmore coin collector, who is president of Harrow Coin Club in north London, has amassed an impressive collection during the past 30 years.

The club is one of the oldest numismatic societies in the country and is somewhere that enthusiasts can exchange coins and listen to guest speakers extolling the benefits of anything from metal detecting to Japanese military currency.

So what’s the attraction of putting your hand in your pocket for money that has lost its value?

“Coins have a way of reflecting significant times and events,” says the retired civil engineer who spent much of his career in far-flung parts of the world like Papua New Guinea and Brazil.

“It’s a fascinating subject. Once you start reading about the history surrounding a coin, one thing leads to another.”

Rex’s globe trotting career has allowed him to build an extensive collection of several thousand coins along with paper money and tokens.

His oldest coin dates back to the reign of Alfred the Great more than 1,000 years ago when Britain’s shores were under siege from Viking raiders.

Surprisingly, older currency is not as rare or expensive as you might imagine. And much of that is down to the work of metal detector enthusiasts.

A silver drachma from the reign of Alexander the Great can cost as little as £30, while a silver denarius from one of the early Roman emperors can cost just £15.

Not that some coins don’t cost a pretty penny.

The most expensive tend to be limited issues that never make it into public circulation such as an 1933 American double eagle, which sold at auction for £4.1m.

Nearly half-a-million were produced during the height of the Depression but a dispute over the design led to them being scrapped and melted down.

US Treasury officers later discovered that ten of the coins had disappeared. Nine were recovered but the tenth eluded their grasp and later turned up in a private collection owned by the King of Egypt.

It disappeared again in the mid-1950s before resurfacing in 1996 when a British coin dealer attempted to sell it to Government undercover agents in New York.

Things are decidedly less racy at Harrow Coin Club but Rex puts his monetary talents to good use by helping sell coin collections donated to local charities.

He said: “I usually manage to raise about £10,000 a year on their behalf. The collections are often donated when someone dies and no-one else in the family is interested in the hobby.”

Harrow Coin Club meets bi-monthly throughout the year except in July and August. Anyone with an interest is welcome to attend. For details, ring Rex Edwards on 020 8952 8765.